Artificial organs would be superior to ordinary donor organs in several ways. They can be made to order more quickly than a donor organ can often be found; being grown from a patient's own cells, they also do not require dangerous immunosuppressant drugs to prevent rejection.

Building the scaffolding was slowed by this being a first-time effort, explains Seifalian. In future, he says, they could build a complete scaffold from CT scans in two days.

Replacement organs have been grown, and implanted, in the past, using a patient's cells and a donor organ stripped of its tissue, with the remaining cartilage to serve as a scaffold for tissue growth. In 2006, a team at the McGowan Institute for Regenerative Medicine in Pittsburgh successfully implanted lab-grown bladders in children with spina bifida. Synthetic scaffolding had been created previously, but it had not been used to replace a human organ.

In conjunction with lines of research like organ printing, this pace of work bodes well for the 2030s as a time in which failing or badly injured organs are no longer automatically fatal or the cause of lifelong disability for the young. There is still the question of how best to take advantage of this for the old, however: the frailty that comes with aging brings with it a much lower survival rate and success rate for major surgery - and any significant transplant is major surgery. Regrowth of organs alone is not the way to greatly extend the maximum human lifespan on a timescale that matters. Other technologies are needed as well.

One might consider a future bioprinting scenario in which an old body is completely discarded, the brain removed and placed within a printing vat.

I don't think the scenario I've painted above is plausible. It's feasible, but I strongly suspect that other branches of medical technology will make it obsolete before it becomes practical. 2060 is a world and a half away: we're expecting to see transformative medical nanomachinery emerge into widespread use by the 2040s, for example. For my money, a much more likely state of rejuvenation technology for baseline human biology in 2060 is the Strategies for Engineered Negligible Senescence vision: an array of therapies (or nanorobotic implementations) that remove biochemical damage in situ. Vaccines or artificial immune cells to clean out the buildup of unwanted biochemicals, replacing mitochondrial DNA or the mitochondria themselves wholesale, targeted destruction of senescent cells, swapping in new stem cell populations to repair everything else, that sort of thing. This would be less a case of tearing down the house to build a new one and much more a case of ongoing, period renovation.